U.S. patent application number 13/327643 was filed with the patent office on 2012-12-20 for wireless data reader at checkstand.
This patent application is currently assigned to Datalogic Scanning. Invention is credited to Cameron G. Breckenridge, Patrick M. O'Donnell, Jon P.C. Williams.
Application Number | 20120319645 13/327643 |
Document ID | / |
Family ID | 47353174 |
Filed Date | 2012-12-20 |
United States Patent
Application |
20120319645 |
Kind Code |
A1 |
O'Donnell; Patrick M. ; et
al. |
December 20, 2012 |
WIRELESS DATA READER AT CHECKSTAND
Abstract
A checkstand system including a counter surface within which a
plurality of induction charge transmission coils are embedded in or
disposed below the counter at selected charge positions about the
countertop whereby a cordless peripheral, such as a data reader, is
positionable and movable between multiple positions about the
counter surface, the peripheral including an induction charge
receiving coil operative to receive a charge current from one of
the induction charge transmission coils when the peripheral is
placed in proximity of a selected one of the charge positions on
the checkstand. In one configuration, the system includes a
temperature sensing component disposed proximal to an induction
charge transmission coil and a controller operative for receiving a
temperature signal from the temperature sensing component and
adjusting the charge current delivered to the induction charge
transmission coil in response to the signal.
Inventors: |
O'Donnell; Patrick M.;
(Eugene, OR) ; Williams; Jon P.C.; (Eugene,
OR) ; Breckenridge; Cameron G.; (Oregon City,
OR) |
Assignee: |
Datalogic Scanning
Eugene
OR
|
Family ID: |
47353174 |
Appl. No.: |
13/327643 |
Filed: |
December 15, 2011 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61424010 |
Dec 16, 2010 |
|
|
|
Current U.S.
Class: |
320/108 |
Current CPC
Class: |
H02J 7/025 20130101;
H02J 7/0042 20130101; H02J 7/0068 20130101; H02J 50/402 20200101;
H02J 50/12 20160201; H02J 50/90 20160201; H02J 5/005 20130101; H02J
50/005 20200101; H02J 50/40 20160201 |
Class at
Publication: |
320/108 |
International
Class: |
H02J 7/00 20060101
H02J007/00 |
Claims
1. A system for retail checkout comprising a checkstand including a
counter with a counter surface; a plurality of induction charge
transmission coils embedded in or disposed below the counter at
selected charge positions about the checkstand; a cordless
peripheral positionable and movable between multiple positions
about the counter surface, the peripheral including an induction
charge receiving coil operative to receive a charge current from
one of the induction charge transmission coils when the peripheral
is placed in proximity of a selected one of the charge positions on
the checkstand.
2. A system according to claim 1 wherein the peripheral comprises
data reader selected from the group consisting of: a handsfree
scanner; a cradle and removable handheld scanner combination; and a
handheld scanner.
3. A system according to claim 1 further comprising a controller
including drive circuitry operative for controlling charge current
delivered to the induction charge transmission coils; a temperature
sensing component for generating a signal associated with the
temperature of the drive circuitry, wherein the controller is
further operative for receiving the signal and adjusting the charge
current delivered to the induction charge transmission coil in
response to the signal.
4. A system according to claim 1 further comprising an efficiency
monitoring component electrically connected to at least one of the
induction charge transmission coils and establishing a signal
associated with a derived efficiency of the induction charge
transmission coil; a controller operative for receiving the signal
and adjusting the charge current delivered to the induction charge
transmission coil to maintain resonance between the induction
charge transmission coil and the induction charge receiving coil in
response to the derived efficiency.
5. A system according to claim 1 further comprising a controller
operative for sensing presence of peripheral device receiving coil
drawing power from a specific induction charge transmission coil
and for selectively driving only that specific induction charge
transmission coil and removing drive current from other induction
charge transmission coils not in use.
6. A system according to claim 1 wherein the counter surface
includes a lowered shelf section.
7. A method of operation at retail checkout, comprising arranging a
plurality of induction charge transmission coils embedded in or
disposed below a counter at selected charge positions about a
checkstand; moving a cordless peripheral device between multiple
positions about the counter, the peripheral device including an
induction charge receiving coil operative to receive a charge
current from one of the induction charge transmission coils when
the peripheral device is placed on a surface of the counter in
proximity of one of the charge positions.
8. A method according to claim 7 further comprising sensing
presence of a peripheral device receiving coil drawing power from a
specific induction charge transmission coil; selectively driving
only that specific induction charge transmission coil and removing
or reducing drive current from other induction charge transmission
coils not in use.
9. A method according to claim 8 wherein the step of sensing
presence of a peripheral device receiving coil drawing power
comprises monitoring a change in drive current at the specific
induction charge transmission coil.
10. A method according to claim 8 wherein the step of sensing
presence of a peripheral device receiving coil drawing power
comprises monitoring a change in inductance at the specific
induction charge transmission coil.
11. A method according to claim 7 further comprising charging only
the peripheral device by sensing presence of peripheral device
receiving coil drawing power from a specific induction charge
transmission coil and for selectively driving only that specific
induction charge transmission coil and removing drive current from
other induction charge transmission coils not in use.
12. A method according to claim 7 wherein the peripheral comprises
a data reader selected from the group consisting of: a handsfree
scanner; a cradle and removable handheld scanner combination; and a
handheld scanner.
13. A method according to claim 7 further comprising controlling,
via drive circuitry, charge current delivered to the induction
charge transmission coils; sensing temperature at the drive
circuitry and generating a signal associated with the temperature;
adjusting the charge current delivered to the induction charge
transmission coil in response to the signal associated with the
temperature.
14. A charging system comprising: a work surface; a plurality of
induction charge transmission coils embedded in or disposed below
the work surface at selected charge positions; a cordless device
positionable and movable between multiple positions about the
surface, the peripheral including an induction charge receiving
coil operative to receive a charge current from one or more of the
induction charge transmission coils when the peripheral is placed
in proximity of a selected one of the charge positions on the work
surface; a controller operative for sensing presence of peripheral
device receiving coil drawing power from a specific induction
charge transmission coil and for selectively driving only that
specific induction charge transmission coil and removing drive
current from other induction charge transmission coils not in
use.
15. A system according to claim 14 wherein the cordless device
comprises a data reader selected from the group consisting of: a
handsfree scanner; a cradle and removable handheld scanner
combination; and a handheld scanner.
16. A system for charging electrical storage of an electronic
device, comprising at least one induction charge transmission coil
disposed at a selected charge position; a controller including
drive circuitry operative for controlling charge current delivered
to the induction charge transmission coil; a temperature sensing
component for generating a temperature signal associated with the
temperature of the drive circuitry, wherein the controller is
operative for receiving the temperature signal and adjusting the
charge current delivered to the induction charge transmission coil
in response to the temperature signal.
17. A system according to claim 16 wherein the controller is
further operative for sensing presence of an electronic device
receiving coil drawing power from the induction charge transmission
coil and for selectively driving the induction charge transmission
coil.
Description
RELATED APPLICATION DATA
[0001] This application claims priority to provisional application
Ser. No. 61/424,010 filed Dec. 16, 2010, hereby incorporated by
reference.
BACKGROUND
[0002] The field of the present disclosure relates to checkout
systems and more particularly retail checkstands or other checkout
stands (e.g., a parcel distribution station) that incorporate
portable data readers and other electronic devices and/or related
systems and methods of operation.
[0003] Typical checkstands such as at a retail check station
include counter space for accommodating placement of articles to be
scanned. Certain checkstands include both a fixed scanner and a
handheld scanner whereby certain (e.g., smaller) articles may be
scanned by passing them through the scan volume of the fixed
scanner and certain other items (e.g., larger or bulkier items such
as items remaining in the shopping cart) may be preferably scanned
with the handheld scanner. The present inventor has recognized
certain limitations for arrangements and configurations of
checkstands including one or more portable movable devices such as
handheld scanners.
BRIEF DESCRIPTION OF THE DRAWINGS
[0004] FIG. 1 is a diagrammatic view POS checkstand according to a
first embodiment.
[0005] FIG. 2 is a top view of the POS checkstand of FIG. 1 with
some modifications and alternatives.
[0006] FIG. 2A is a diagrammatic view of the countertop of FIG. 2
showing additional details of one configuration.
[0007] FIG. 2B is a diagrammatic view of a countertop according to
an alternate embodiment.
[0008] FIG. 3 is a diagrammatic view of a handheld data reader and
charging station according to an embodiment.
[0009] FIG. 4 is a diagrammatic top plan view of a first
transmission coil configuration.
[0010] FIG. 5 is a diagrammatic top plan view of a second
transmission coil configuration.
[0011] FIG. 6 is a diagrammatic top plan view of a third
transmission coil configuration.
[0012] FIG. 7 is a system diagram of a charging system according to
a preferred embodiment.
[0013] FIG. 8 is a flow chart of a coil sensing methodology
according to a preferred embodiment.
[0014] FIG. 9 is a schematic diagram of a wireless power transfer
system including a temperature control feedback system.
[0015] FIG. 10 is a schematic diagram of an alternative embodiment
of the wireless power transfer and temperature control feedback
systems of FIG. 9.
[0016] FIG. 11 is a flow chart of a process of adjusting a wireless
power system to maintain resonance for optimal power transfer.
DETAILED DESCRIPTION OF EMBODIMENTS
[0017] With reference to the above-listed drawings, this section
describes particular embodiments and their detailed construction
and operation. The embodiments described herein are set forth by
way of illustration only and not limitation. It should be
recognized in light of the teachings herein that there is a range
of equivalents to the example embodiments described herein. Most
notably, other embodiments are possible, variations can be made to
the embodiments described herein, and there may be equivalents to
the components, parts, or steps that make up the described
embodiments.
[0018] For the sake of clarity and conciseness, certain aspects of
components or steps of certain embodiments are presented without
undue detail where such detail would be apparent to those skilled
in the art in light of the teachings herein and/or where such
detail might obfuscate an understanding of more pertinent aspects
of the embodiments. Various types of data acquisition devices, such
as optical data readers are generally known including imaging-based
data readers and laser scanners, both fixed and handheld. For the
purposes of the present description, the terms scanner and data
reader may be used interchangeably.
[0019] FIGS. 1-2 illustrate a retail checkstand 10 according to a
first preferred embodiment, with FIG. 2 illustrating some
alternative configurations as described below. FIG. 1 in particular
illustrates the checkstand 10 having a work surface 20, a POS
terminal 12 with display and input keyboard 13, a barcode scanner
or other data reader (with or without optional weigh scale) 30. The
checkstand 10 may comprise any suitable configuration, but is shown
in this example with an L-shaped counter 20 having a top surface on
which articles to be scanned and checked out are placed.
Technically speaking, the counter shape is illustrated as an
inverted "L" (as viewed from a top, downwardly-facing viewpoint)
with flow of articles being from right to left from the perspective
of an operator standing in the position designated by the "X" on
the floor. If the counter were arranged with a left to right item
flow, the counter would have a non-inverted L-shape. The counter 20
is shown with a first/front section 20a (at the bottom of the "L"),
a center section 20b, and a rear section 20c. The checkstand 10 is
also shown with a lowered counter section or bagging section 20d.
The bagging section 20d may include a bag rack 16 illustrated in
FIG. 2. A second bag rack 17 may be included proximate the counter
front section 20a.
[0020] FIG. 1 illustrates a first embodiment with cordless/movable
data reader 30 shown resting on the counter first section 20a. The
data reader 30 is shown as a vertical window scanner having an
external configuration similar to the Magellan.RTM. 1100i of
Datalogic Scanning, Inc. in Eugene, Oreg. The data reader 30 is
preferably a cordless, free-standing unit that can be moved about
the countertop 20 and located/aimed at any desired position. The
data reader 30 may comprise a handsfree style of reader whereby
items to be read are presented to or passed through the read zone
in front of the reader window. Such a cordless unit may be easily
repositioned at various locations about the counter because there
is no cord to tangle with other components or otherwise interfere
with the movement/scanning of items. The data reader 30 is provided
with an internal power source (e.g., a rechargeable battery) that
is charged by an inductive charging system. The reader 30 has an
induction coil disposed proximate a bottom surface thereof. The
counter 20 is constructed with a charging area 22 comprised of an
induction coil charging array of a suitable configuration as will
be described in more detail below. As illustrated in both FIGS. 1
and 2, the charging array 22 is positioned in the counter front
section 20a, but the charging array may be positioned at any
suitable location, and the checkout station 10 may include one or
more charging areas.
[0021] FIG. 2 illustrates an alternate style of data reader
comprising a handheld reader 32. The checkout counter 20 is further
shown with an optional in-counter reader 18 which may comprise a
single window reader, such as the Magellan.RTM. 2300HS or a
multi-window reader, such as the Magellan.RTM. 8500 scanner-scale,
both from Datalogic Scanning, Inc., Eugene, Oreg.). Items 5, 6
brought to the counter 20 via conveyor 3 may then be scanned either
by the in-counter reader 18 or the handheld reader 32. Large or
bulky items that might be left in the shopping cart may also be
scanned by the handheld reader 32.
[0022] FIG. 2 also illustrates several positions for the charging
area, such as charging area 22 in the counter forward section;
charging area 24 to the right side of the POS terminal 12; charging
area 26 in the counter center section 20b to the front side of the
POS terminal 12; charging area 28 in the counter rear section 20c;
or in the bagging area shelf 20d. Alternately, it may be
advantageous to locate the charging area in a position which is
less accessible to the customer. For example, the charging position
26 is, relative to the customer, behind the POS terminal 12 and
thus somewhat blocked from view/access to the customer. A charging
area 29 is shown positioned on the lower bagging shelf 20d and thus
is below and behind the countertop 20.
[0023] Alternately, as shown in FIG. 1, the counter 20 may include
a specialized lower shelf 40 having a charging area 42. The
handheld reader may be then placed on the shelf somewhat out of
sight and out of reach of the customer. In yet another alternative,
the countertop 20 may be supplied with a recess or slot 44 into
which the cordless reader 32 may be inserted, the slot including a
charging area therein.
[0024] FIG. 3 illustrates an example configuration for a data
reader 50 of the handheld/portable type. The handheld data reader
50 is similar to the reader 32 shown in FIG. 2. The reader 50
includes a housing unit 52 having a handle section 54, a head or
upper section 56 and a lower or foot section 58. Though illustrated
in an exploded view, the lower section 58 is connected (either
pivotally or non-pivotally) to the base section 60 in a suitable
fashion. The base 60 serves as a platform for supporting the reader
housing 52 onto a horizontal surface such as the countertop 20. In
one optional configuration, the unit may comprise a built-in stand
whereby the housing 52 remains connected to the base 60 when
operated either in the handheld/portable mode or self-supporting in
a hands-free operating mode. The cordless unit 50 may communicate
wirelessly (such as via antenna 66) with the scanner 30, the host
or other controller. The host or controller may be included within
the POS 12, for example. The handheld unit 50 includes a battery 64
(shown schematically in the figure) which is rechargeable type
operably connected to a power supply and induction receiving coil
62. Alternately, the cordless unit may communicate to a receiver
disposed in base 70 which has a wired connection 74 to the host.
The battery 64 may be located in any suitable location either in
the housing 52 or the base section 60. Power is transferred
wirelessly from the charging unit 70 disposed below the surface of
the countertop 20 via transmission from induction transmission coil
72 of the charging unit 70 to the induction receiving coil 62 in
the base section 60 thus requiring no physical electrical contact
between the base section 60 and the induction charging unit 70. A
calibration switch 73 is used to establish resonance between the
induction transmission coil 72 and the receiving coil 62. The
induction charging unit 70 is suitably connected to a controller
and power supply via cable 74, but the cable 74 is positioned
beneath the counter surface and keeps the top surface clear of
cords thus does not interfere with movement of items about the
countertop 20.
[0025] In one example configuration, it is envisioned that there
will be multiple charging coil units 70 (of any suitable style or
arrangement) arranged about the countertop thus enabling the cradle
section 60 to be placed in any suitable location (proximate a
charging coil) and be charged.
[0026] In another configuration of the scanner unit 50, the scanner
portion 52 may be removable from the base portion 60 (which may be
configured as a cradle) with a battery 53 on board the scanner
portion being charged from the receiving coil 62 to electrical
contacts 76a, 76b and then to mating electrical contacts 75a, 75b
in the scanner portion. Though the scanner portion 52 is
illustrated to be placed in the cradle portion 60 so as to be
disposed in a vertical orientation, other cradle configurations are
envisioned. For example, a larger/wider cradle may be constructed
that accepts the scanner portion in a more laid down or horizontal
orientation.
[0027] Having multiple charging areas about the countertop allows
the user to place peripheral devices, such as the scanners 30, 32,
50, or even other devices such as the POS terminal 12, at any
convenient location. The checkstand 10 may thus assume many
different configurations depending on operational needs or personal
preference without requiring re-wiring or interfering cable
positioning. For certain peripheral devices such as the POS
terminal 12, additional connecting/securing mechanism may be
optionally included to reduce possibility of tipping.
[0028] The scanner 30, 32, 50 or the cradle unit/base 60 may be
provided with charging indicators, such as LED lighting, that
alight indicating that the unit has been placed/aligned suitably
over a charging coil. The lighting may be controlled to
increase/decrease in intensity to assist a user in positioning the
scanner or cradle in an optimum position over a charging coil.
Where the countertop is equipped with multiple discrete charging
locations, the top surface may be configured with suitable surface
markings to indicate charging "hot spots" to assist the user in
placing the reader in an optimum charging location.
[0029] The induction transmission coils themselves may comprise any
suitable configuration. FIG. 4 illustrates an array 80 of toroidal
coils 82 placed in such a way as to allow a peripheral fitted with
a receiving coil to be placed in many locations on the work
surface. The array 80 of one or more coils 82 may comprise a
charging section, such as charging sections 22, 24, 26, etc. in the
countertop 20 as shown in FIGS. 1-2.
[0030] FIG. 2 illustrates discrete placement of coils or coil
arrays arranged about the countertop and FIG. 2A illustrates an
example configuration for the coil arrays, with one or more coils
82 disposed within each of the coil placement sections. In this
configuration of countertop 20, the coil array section 22 has nine
coils 82; coil array sections 24, 26 each have three coils 82; coil
array sections 16 and 28 each have six coils 82; and coil array
section 29 has one coil 82.
[0031] FIG. 2B illustrates an alternate configuration whereby the
entire countertop 20 (or a substantial portion thereof) may be
fitted with transmission coils 82. In such a configuration, the
handheld reader may be positioned above a charge coil no matter
where it is placed on the countertop section. As shown the coils
may be arranged in a grid pattern (as shown on the left side of the
figure, or counter section 20c) or a more random pattern (as shown
on the right side of the figure, or counter section 20a). The coils
may thus be arranged in any suitable configuration or density.
[0032] Coil types can take any suitable form. FIG. 5 shows an array
85 of flat spiral wound coils 87 placed in such a way as to allow
many locations in which a peripheral could be placed at various
positions about the work surface and still receive induction
charging power.
[0033] FIG. 6 illustrates another power coil arrangement 90 in
which a single coil 92 is formed by laying magnetic wire in a
switch back arrangement. Again this layout provides many locations
in which a peripheral (bar code scanner, display, weigh scale)
could be placed at various positions on the work surface and still
receive power.
[0034] Where the checkstand is equipped with multiple charging
coils, drive electronics may drive all the coils at once even
though only one coil might be in use with the device on the work
surface. In a preferred embodiment, as shown in FIG. 7, a control
system 100 is provided (e.g. controller 108) whereby the drive
electronics sense presence of a device 102 with a receiving coil
104 drawing power from a specific coil 106b and selectively driving
only that coil, removing drive current from those other coils 106a,
106c not in use. The sensing may comprise circuitry that monitors a
change in drive current or a change in inductance as a peripheral
device 102 placed within proximity of the specific transmission
coil 106b. Such a drive control system may advantageously increase
efficiency of the wireless power charging system.
[0035] FIG. 8 is a flow chart for a coil sensing methodology 150
according to a first embodiment. This example describes a three
coil system, but the concept may be expanded to as many coils as
would be needed for a particular wireless checkstand
implementation. Starting at Step 152, the first step at Step 154 is
to check or measure either the voltage or the current of a first
coil (Coil 1) in response to a stimulus signal, and then at Step
156 store that value for future reference. Each coil in the stand
would be measured which provides a beginning initialization. In
this three coil example, the second coil (Coil 2) is checked at
Step 158, and the voltage/current value for Coil 2 is stored at
Step 160. Then the third coil (Coil 3) is checked at Step 162, and
the voltage/current value for Coil 3 is stored at Step 164.
[0036] Once all the coils have been checked and initial values
stored, the current/voltage value of Coil 1 is again measured with
the same stimulus signal at Step 166 and then determined at Step
168 if the Coil 1 value has changed. If No, proceed to Step 176 to
check Coil 2; if Yes, proceed to Step 170 to determine whether Coil
1 is on. If it is determined at Step 170 that Coil 1 is on (Yes),
proceed to Step 172 and turn Coil 1 drive off then proceed to Step
176. If at Step 170 it is determined that Coil 1 is not on (No),
proceed to Step 174 and turn on Coil 1 drive then proceed to Step
176.
[0037] Having dealt with Coil 1, the method proceeds to Step 176 to
check Coil 2 whereby the current/voltage value of Coil 2 is again
measured and then determined at Step 178 if the Coil 2 value has
changed. If No, proceed to Step 186 to check Coil 3; if Yes,
proceed to Step 180 to determine whether Coil 2 is on. If it is
determined at Step 180 that Coil 2 is on (Yes), proceed to Step 182
and turn Coil 2 drive off then proceed to Step 186. If at Step 180
it is determined that Coil 2 is not on (No), proceed to Step 184
and turn on Coil 2 drive then proceed to Step 186.
[0038] Having dealt with Coils 1 and 2, the method proceeds to Step
186 to check Coil 3 whereby the current/voltage value of Coil 3 is
again measured and then determined at Step 188 if the Coil 3 value
has changed. If No, return/cycle back to Step 166 to again check
Coil 1; if Yes, proceed to Step 190 to determine whether Coil 3 is
on. If it is determined at Step 190 that Coil 3 is on (Yes),
proceed to Step 192 and turn Coil 3 drive off then proceed to Step
196. If at Step 190 it is determined that Coil 3 is not on (No),
proceed to Step 194 and turn on Coil 3 then proceed to Step 196. By
this process of monitoring the coil current or voltage, it can be
determined if a wireless peripheral has been placed over the coil
or removed from the proximity of the coil.
[0039] FIGS. 9 and 10 illustrate schematic diagrams for alternative
embodiments of wireless power systems suitable for powering or
charging data readers. Identical components share common numerical
labels in FIGS. 9 and 10.
[0040] The schematic in FIG. 9 illustrates a wireless power system
200 embodiment. The wireless power system 200 includes drive
circuitry 202 for driving a power-transmitting coil 204 to induce
an electromagnetic field in a gap 205. Across the gap 205, the
wireless power system 200 includes a power-receiving coil 206 with
associated receiving circuitry 207 to convert the received
oscillating power into a steady DC voltage, or alternatively, a
steady current. Power is wirelessly transferred between the two
coils (204, 206) when the drive circuitry 202 produces a
peak-to-peak signal to drive the power-transmitting coil 204 and
inductively couple the power-receiving coil 206. The associated
receiving circuitry 207 shown in FIG. 9 converts the oscillating
received power into a steady DC voltage used to power electronics
such as the cordless/movable data reader 30 or handheld reader 32
described above.
[0041] For maximum efficiency, inductive power transfer systems
should ideally operate in resonance. Power-transmitting and
power-receiving coils 204 and 206 are each paired with capacitors
208 and 210 to form resonant tank circuits that are ideally driven
at their natural resonant frequency. The power-transmitting coil
204 and the capacitor 208 form a power-transmitting resonant tank
circuit 211, coupled in close proximity to a power-receiving tank
circuit 212 comprised of the power-receiving coil 206 and the
capacitor 210. The components in the power-transmitting and
power-receiving resonant tank circuits are selected so the tank
circuits have matching resonant frequencies.
[0042] The drive circuitry 202 includes a microcontroller
(.mu.Controller) 213 with an output 214 in series with a resistor
216. The output 214 drives a gate 218 of a switching N-channel
MOSFET transistor 219 with a 5-volt peak-to-peak square wave signal
that produces current flow in the power-transmitting coil 204. The
current flow is sourced from a voltage source (Vd) 220 and
continues through the power-transmitting coil 204. The current
exits a source 220 of the transistor 219 and produces a monitoring
voltage (VRsense) 221 across a resistor (Rsense) 222. The
monitoring voltage 221 is measured from a connection 224 at an
input 225 of an analog to digital converter (A/D converter) 226.
The A/D converter 226 samples the monitoring voltage 221 and
provides a digital value of the voltage 221 to the microcontroller
213 along a connection 227. The microcontroller 213 reads the
digital value and adjusts the drive frequency signal to ensure that
the power-transmitting coil 204 and power-receiving coil 206
operate in resonance.
[0043] On the power-receiving side, a diode 228 and a reservoir
capacitor 230 form the associated receiving circuitry 207. The
associated receiving circuitry converts the received oscillating
power into a DC voltage to power an electrically connected load
232.
[0044] FIG. 9 also illustrates an optional temperature control
feedback system 250 operative to increase the control and response
of the wireless power transfer system 200 in situations where the
system 200 is operating in non-resonant modes. These non-resonant
modes can arise when an object, other than the power-receiving coil
206, is placed in close proximity to the power-transmitting coil
204 such that the object inductively couples with the
power-transmitting coil 204 in a non-resonant or inefficient
manner. If the wireless power transfer system 200 becomes
non-resonant, the efficiency of the system 200 decreases and as a
result, component(s) in the drive circuit 202 can heat up. Using a
thermal sensor to detect a heat increase provides an indication
that the wireless power transfer system 200 has become
non-resonant. When this heat increase is detected, the drive
frequency signal can be shut down thereby protecting both the
power-transmitting coil 204 and any coupled object. An advantage of
the temperature control feedback system 250 is that all of the
temperature detection and control components are contained on the
transmitting side of the wireless power transfer system 200 so no
direct communication between the receiving circuitry 207 and the
drive circuitry 202 is necessary.
[0045] FIG. 9 depicts a temperature sensitive electronic component
(Device temp) 252, such as a thermistor, thermocouple, or other
suitable device(s) in relatively close proximity to the drive
circuitry 202 (particularly the MOSFET transistor 219) of the
wireless power transfer system 200. With the addition of the Device
temp component(s) 252, the wireless power transfer system 200 can
react or shutdown to prevent damage if the MOSFET transistor 219 or
any other components overheat. The Device temp component 252 reacts
to changes in temperature of the transistor 219, and provides a
device temperature feedback voltage to the A/D converter 226. The
A/D converter 226 first, (1) receives the device temperature
feedback voltage along an electrical connection 254 and converts
the voltage into a digital value; and second (2) provides the
digital value to the microcontroller 213 along an electrical
connection 256.
[0046] Another temperature sensitive electronic component (Ambient
temp) 254, produces an ambient temperature voltage in proportion to
the ambient temperature. The A/D converter 226 first, (1) receives
the ambient temperature voltage along an electrical connection 260
and converts the voltage into a digital value; and second, (2)
provides the digital value to the microcontroller 213 along an
electrical connection 262. By using two thermal sensors, Device
temp 252 and Ambient temp 254, the increase in the drive circuit
202 temperature may be isolated from any increase in ambient
temperature to thereby approximate the total amount of energy
dissipated. The total amount of energy is calculated in software
with the microcontroller 213 subtracting the ambient temperature
value from the device temperature feedback. Alternatively, ambient
temperature voltages may be subtracted in hardware using a
differential operational amplifier configuration.
[0047] FIG. 10 is a schematic illustrating alternative embodiments
of wireless power transfer and temperature control feedback
systems. As in FIG. 9, a wireless power transfer system 300 in FIG.
10 includes drive circuitry 302 for driving the power-transmitting
coil 204, and a power-receiving coil 206 with associated
power-receiving circuitry 304 to convert the oscillating received
power into a steady DC voltage, or alternatively, a steady current.
The drive circuitry 302 produces a peak-to-peak signal to drive the
power-transmitting coil 204 to induce an electromagnetic field. The
power-receiving coil 206 is inductively coupled to the
power-transmitting coil 204, which permits wireless power transfer.
The associated receiving circuitry 304 converts the received power
into a steady DC voltage used to power or charge a load 232. The
power-transmitting coil 204 and power-receiving coil 206 are paired
with the capacitors 208 and 210 to form resonant tank circuits that
are ideally driven at their natural resonant frequencies as
described in FIG. 9.
[0048] The drive circuitry 302 includes a microcontroller 308. A
suitable microcontroller is the model MSP430 available from Texas
Instruments of Dallas, Tex. The microcontroller 308 has an output
310 that is connected to each buffer input of a quad buffer
(Buffer) 312. A suitable Buffer 312 is the model 74LV125 available
from NXP Semiconductors of Eindhoven, Netherlands. The Buffer 312
outputs are electrically combined and connected to the gate 218 of
the switching N-channel MOSFET transistor 219. In this arrangement,
the microcontroller 308 generates a 5-volt peak-to-peak square
wave, preferably at 407 kHz, that is buffered and used to drive the
gate 218 of the transistor 219 to produce current flow in the
power-transmitting coil 204.
[0049] In FIG. 10, the resistor 222 is connected in series between
a voltage source 316 and the transmitting resonant tank circuit
211. The transmitting resonant tank circuit 211 is then connected
in series to a drain 318 of the transistor 219. It may be observed
that despite the slightly different arrangement of the resistor 222
from FIG. 9, the resistor 222 may function in essentially the same
way for both FIGS. 9 and 10. The current flowing from the voltage
source 316 flows into the resistor 222 to produce the monitoring
voltage 221 across the resistor 222 that is used to monitor the
current flowing into the drain 318 of the transistor 219. The
arrangement in FIG. 10 allows two different voltage sources to be
used on the transmitter side: (1) the voltage source 316 is used
for producing higher power in the power-transmitting coil, and (2)
another lower power voltage source 320 is used for powering digital
integrated circuits such as the microcontroller 308 and the Buffer
312. The configuration of voltage source 316 and resistor 322
includes an additional shunt capacitor 322.
[0050] FIG. 10 also illustrates that the voltage drop across the
resistor 222 is measurable with increased resolution by using a
differential operational amplifier 324 and two matching sets of
voltage dividers established principally by resistors 326, 328,
330, and 332. A suitable operational amplifier 324 is the model
LM321 available from National Semiconductor of Santa Clara, Calif.
The differential operational amplifier 324 is biased for
common-mode rejection with equal input resistors 334 and 336, and a
feedback resistor 338 with resistance equal to a gain resistor 340.
Because the operational amplifier 324 is set up in one example in a
differential configuration with a gain of 1000, the measurable
voltage drop across the resistor 222 is much more sensitive than
the single-ended configuration of FIG. 9. Thus, the analog to
digital converter module built within microcontroller 308 may
sample the monitoring voltage 221 with higher resolution and
provide a higher precision digital value. As in the previous
embodiment, the microcontroller 308 reads the digital value to
adjust the drive frequency signal to ensure that the
power-transmitting coil 204 and power-receiving coil 206 operate in
resonance.
[0051] On the power-receiving side, as shown in FIG. 9, the diode
228 and the reservoir capacitor 230 of FIG. 10 form the associated
receiving circuitry 304 and function the same way as in FIG. 9,
i.e., to convert the oscillating received power into a DC voltage.
However, associated receiving circuitry 304 includes an additional
DC/DC converter 342 to regulate the DC voltage. A suitable DC/DC
converter is the model TPS54160 available from Texas Instruments of
Dallas, Tex.
[0052] A temperature control feedback system 350 is illustrated in
FIG. 10 as a thermal sensor 352 with one side connected to ground,
and the other side forming a voltage divider circuit with a
resistor 354 that is connected to the voltage source 320. As in the
previous example of FIG. 9, the thermal sensor 352 is near
transistor 219 such that the wireless power transfer system 300 can
react or shutdown if the MOSFET transistor 219 or other components
overheat. Unlike FIG. 9 however, only one thermal sensor is
present. The thermal sensor 352 produces a voltage measurement
corresponding to the temperature of the drive circuit 302 in
ambient conditions. The analog to digital converter module inside
the microcontroller 308 receives and converts the temperature
measurement into a digital value. The microcontroller 308 checks
the digital value against programmed temperature limits and adjusts
the drive signal accordingly.
[0053] A properly configured resonant power transfer system is much
more efficient than a transformer coupled system like that of a
toothbrush charger, which has low efficiency. However, for a
resonant power transfer systems to operate efficiently, i.e., at
optimum power transfer, the drive signal frequency is preferably
adjusted to establish resonance in the transmitting and receiving
coils. FIG. 11 depicts a flow chart for a process 400 of adjusting
a wireless power system such that the power-transmitting and
power-receiving coils maintain resonance. Adjustment may take place
when the data reader 50, depicted in FIG. 3, is placed on the
charging unit 70. Calibration may be initiated manually with a user
input, e.g., actuating the calibration switch 73 (shown in FIG. 3),
or automatically with the microcontroller sensing the presence of a
power-receiving coil. In either case, the microcontroller adjusts
the drive frequency of the charging unit 70 to establish optimum
power transfer. The drive frequency can then be stored to
facilitate mating of the charging unit 70 and the data reader 50.
If the data reader 50 is later replaced, the calibration process
can be executed again to ensure optimum performance with a new data
reader.
[0054] Turning to FIG. 11, a preferred process 400 adjusting a
charging system includes the following steps: Step 401, the data
reader 50 is placed on the charging unit 70, calibration is
initiated, and the process proceeds to Step 402.
[0055] Step 402: the system turns the drive frequency on, sets the
frequency to a specified initial frequency selected to be less than
a nominal resonant frequency, stores an initial voltage measurement
221 across the resistor 222, and proceeds to Step 404.
[0056] Step 404: checks the temperature of the drive transistor 219
and associated components to ensure operation within safe
temperature limits. As discussed above with reference to FIG. 9,
the temperature may be measured by comparing the ambient
temperature to that of the drive circuit 202, or without ambient
temperature as depicted in FIG. 10. If the device exceeds a high
temperature threshold at Step 404 (Yes), the process proceeds to
Step 406, otherwise it proceeds to Step 412.
[0057] Step 406: shuts off the drive if the device exceeds a high
temperature threshold at Step 404 (Yes) and proceeds to Step
408.
[0058] Step 408: waits for a configurable time and proceeds to Step
410.
[0059] Step 410: rechecks the temperature. If the temperature has
cooled below a cool down temperature limit at Step 410 (Yes) the
process begins again at Step 402, otherwise the process proceeds to
Step 408.
[0060] Step 412: checks whether the drive frequency is less than
the Final step frequency when the device does not exceed a high
temperature threshold at Step 404 (No). If the drive frequency is
less than the Final step frequency at Step 412 (No) the process
proceeds to Step 414, otherwise the process proceeds to Step
424.
[0061] Step 414: increments the present drive frequency by some
pre-configured incremental step frequency when the drive frequency
is determined to be less than the Final step frequency at Step 412
(No). The process proceeds to Step 416.
[0062] Step 416: measures the voltage across the resistor 222 to
generate the differential or single-ended voltage measurement,
VRsense, and proceeds to Step 418.
[0063] Step 418: checks whether the newly measured VRsense is less
than the value of the stored VRsense measurement. If the new
VRsense is less than the stored VRsense at Step 418 (Yes) the
process proceeds to Step 420, otherwise at Step 418 (No) the
process proceeds to Step 422.
[0064] Step 420: the new VRsense measurement from Step 416 and
associated drive frequency from Step 414 are stored. Step 420 then
process proceeds back to Step 412.
[0065] Step 422: the new VRsense measurement from 416 and
associated drive frequency from Step 414 are discarded if at Step
418 (No) the new VRsense is not less than the stored VRsense value.
Step 422 then process proceeds to Step 412.
[0066] Steps 412-422 are repeated until the drive frequency is
incremented over a pre-specified range in order to find the
resonant frequency of the coils.
[0067] Step 424: the drive frequency is set to the stored frequency
from Step 420 when the drive frequency exceeds the Final step
frequency at Step 412 (Yes). The process proceeds to Step 426.
[0068] Step 426: calibration is complete.
[0069] The system for charging an electrical storage (e.g.,
battery) of an electronic device (e.g., cordless data reader)
described above may be implemented on a single induction charge
transmission coil at a selected charge position (e.g., embedded in
a counter or wall) or a system of multiple induction charge
transmission coils disposed at a selected charge positions. Thus in
one configuration, the system includes least one induction charge
transmission coil; a controller including drive circuitry operative
for controlling charge current delivered to the induction charge
transmission coil; a temperature sensing component for generating a
temperature signal associated with the temperature of the drive
circuitry, wherein the controller is operative for receiving the
temperature signal and adjusting the charge current delivered to
the induction charge transmission coil in response to the
temperature signal. Optionally, the controller may be further
operative for sensing presence of an electronic device receiving
coil drawing power from the induction charge transmission coil and
for selectively driving the induction charge transmission coil.
Where the system includes multiple induction charge transmission
coils, the controller may be further operative for sensing presence
of an electronic device receiving coil drawing power from one or
more of the induction charge transmission coils and for selectively
driving each of the induction charge transmission coils drawing
power.
[0070] Though described primarily with respect to a
checker-assisted data reader, the readers and methods described
herein may be employed in a self-checkout system.
[0071] It is intended that subject matter disclosed in one portion
herein can be combined with the subject matter of one or more of
other portions herein as long as such combinations are not mutually
exclusive or inoperable.
[0072] The terms and descriptions used above are set forth by way
of illustration only and are not meant as limitations. Those
skilled in the art will recognize that many variations can be made
to the details of the above-described embodiments without departing
from the underlying principles of the invention.
* * * * *